<template>
  <view class="uni-numbox">
    <view @click="_calcValue('minus')" class="uni-numbox__minus uni-numbox-btns" :style="{ background }">
      <text class="uni-numbox--text" :class="{ 'uni-numbox--disabled': inputValue <= min || disabled }" :style="{ color }">-</text>
    </view>
    <input :disabled="disabled" @focus="_onFocus" @blur="_onBlur" class="uni-numbox__value" type="number" v-model="inputValue" :style="{ background, color }" />
    <view @click="_calcValue('plus')" class="uni-numbox__plus uni-numbox-btns" :style="{ background }">
      <text class="uni-numbox--text" :class="{ 'uni-numbox--disabled': inputValue >= max || disabled }" :style="{ color }">+</text>
    </view>
  </view>
</template>
<script>
/**
 * NumberBox 数字输入框
 * @description 带加减按钮的数字输入框
 * @tutorial https://ext.dcloud.net.cn/plugin?id=31
 * @property {Number} value 输入框当前值
 * @property {Number} min 最小值
 * @property {Number} max 最大值
 * @property {Number} step 每次点击改变的间隔大小
 * @property {String} background 背景色
 * @property {String} color 字体颜色（前景色）
 * @property {Boolean} disabled = [true|false] 是否为禁用状态
 * @event {Function} change 输入框值改变时触发的事件，参数为输入框当前的 value
 * @event {Function} focus 输入框聚焦时触发的事件，参数为 event 对象
 * @event {Function} blur 输入框失焦时触发的事件，参数为 event 对象
 */

export default {
  name: 'UniNumberBox',
  emits: ['change', 'input', 'update:modelValue', 'blur', 'focus'],
  props: {
    value: {
      type: [Number, String],
      default: 1
    },
    modelValue: {
      type: [Number, String],
      default: 1
    },
    min: {
      type: Number,
      default: 0
    },
    max: {
      type: Number,
      default: 100
    },
    step: {
      type: Number,
      default: 1
    },
    background: {
      type: String,
      default: '#f5f5f5'
    },
    color: {
      type: String,
      default: '#333'
    },
    disabled: {
      type: Boolean,
      default: false
    }
  },
  data() {
    return {
      inputValue: 0
    };
  },
  watch: {
    value(val) {
      this.inputValue = +val;
    },
    modelValue(val) {
      this.inputValue = +val;
    }
  },
  created() {
    if (this.value === 1) {
      this.inputValue = +this.modelValue;
    }
    if (this.modelValue === 1) {
      this.inputValue = +this.value;
    }
  },
  methods: {
    _calcValue(type) {
      if (this.disabled) {
        return;
      }
      const scale = this._getDecimalScale();
      let value = this.inputValue * scale;
      let step = this.step * scale;
      if (type === 'minus') {
        value -= step;
        if (value < this.min * scale) {
          return;
        }
        if (value > this.max * scale) {
          value = this.max * scale;
        }
      }

      if (type === 'plus') {
        value += step;
        if (value > this.max * scale) {
          return;
        }
        if (value < this.min * scale) {
          value = this.min * scale;
        }
      }

      this.inputValue = (value / scale).toFixed(String(scale).length - 1);
      // TODO vue2 兼容
      this.$emit('input', +this.inputValue);
      // TODO vue3 兼容
      this.$emit('update:modelValue', +this.inputValue);
      this.$emit('change', +this.inputValue);
    },
    _getDecimalScale() {
      let scale = 1;
      // 浮点型
      if (~~this.step !== this.step) {
        scale = Math.pow(10, String(this.step).split('.')[1].length);
      }
      return scale;
    },
    _onBlur(event) {
      this.$emit('blur', event);
      // 官方的代码没有进行数值转换，用户输入的 value 值可能是非法字符：
      // let value = event.detail.value;
      // 将用户输入的内容转化为整数
      let value = parseInt(event.detail.value);
      if (!value) {
        // 如果转化之后的结果为 NaN，则给定默认值为 1
        this.inputValue = 1;
        return;
      }
      if (isNaN(value)) {
        this.inputValue = this.min;
        return;
      }
      value = +value;
      if (value > this.max) {
        value = this.max;
      } else if (value < this.min) {
        value = this.min;
      }
      const scale = this._getDecimalScale();
      this.inputValue = value.toFixed(String(scale).length - 1);
      this.$emit('input', +this.inputValue);
      this.$emit('update:modelValue', +this.inputValue);
      this.$emit('change', +this.inputValue);
    },
    _onFocus(event) {
      this.$emit('focus', event);
    }
  }
};
</script>
<style lang="scss">
$box-height: 26px;
$bg: #f5f5f5;
$br: 2px;
$color: #333;

.uni-numbox {
  /* #ifndef APP-NVUE */
  display: flex;
  /* #endif */
  flex-direction: row;
}

.uni-numbox-btns {
  /* #ifndef APP-NVUE */
  display: flex;
  /* #endif */
  flex-direction: row;
  align-items: center;
  justify-content: center;
  padding: 0 8px;
  background-color: $bg;
  /* #ifdef H5 */
  cursor: pointer;
  /* #endif */
}

.uni-numbox__value {
  margin: 0 2px;
  background-color: $bg;
  width: 40px;
  height: $box-height;
  text-align: center;
  font-size: 14px;
  border-left-width: 0;
  border-right-width: 0;
  color: $color;
}

.uni-numbox__minus {
  border-top-left-radius: $br;
  border-bottom-left-radius: $br;
}

.uni-numbox__plus {
  border-top-right-radius: $br;
  border-bottom-right-radius: $br;
}

.uni-numbox--text {
  // fix nvue
  line-height: 20px;

  font-size: 20px;
  font-weight: 300;
  color: $color;
}

.uni-numbox .uni-numbox--disabled {
  color: #c0c0c0 !important;
  /* #ifdef H5 */
  cursor: not-allowed;
  /* #endif */
}
</style>
